TPEs are block co-polymers made of a hard component and a soft component. The two components undergo microphase separation. The solid domains formed by the hard component are glassy or crystalline. The solid domains are dispersed within a matrix of the soft component and act as both physical crosslinkers and filler particles. The polymer chains of the soft component have a Tg below the service temperature and are able to stretch but are restricted from flowing. In the absence of the hard component, the soft component can flow. TPE networks can be recycled, and can be prepared by liquid processing technologies.
In conventional TPEs, the molecular weights of the hard and soft components have to reach a relatively high value for effective microphase separation. Even after the above molecular weight requirements are satisfied, there is still a certain degree of mixing in the microdomains. The incomplete segregation often compromises the materials properties causing problems such as plastic deformation. For block copolymer TPEs, where the block responsible for physical crosslink is usually a styrenic block, the service temperature cannot exceed the glass transition temperature of polystyrene (Tg=˜90° C.), which significantly limits their usefulness.
Accordingly, there is a need in the art for a TPE having “hard” components with adjustable Tg's and/or melting temperature (Tm) that are higher than the Tg of the prior art polystyrene components, a high microphase separation tendency, and low plastic deformation.